(1) Field of the Invention
The present invention relates to a bearing device.
(2) Description of Related Art
Recently, in a bearing device of an accessory such as an oil pump and a fuel injection pump for an internal combustion engine for a car, there has been used a bearing housing made of an Al alloy for weight reduction of the internal combustion engine.
JP-A-2009-228725 (see paragraphs [0002], [0003], [0013] and the like) discloses a sliding bearing in which a multilayer material composed of a Fe alloy back metal layer and a bearing alloy layer is formed into a cylindrical shape such that the Fe alloy back metal layer becomes an outside diameter side. A surface of the bearing alloy layer supports a corresponding shaft, and strength of the sliding bearing mainly relates to the Fe alloy back metal layer. The sliding bearing is press-fitted into a bearing holding hole of a bearing housing, fixed, and used. More specifically, the outside diameter (outer circumferential length) of the sliding bearing is set to be slightly larger than an inside diameter (inner circumferential length) of the bearing holding hole of the bearing housing, and this size difference is called an interference. With this interference, when the sliding bearing is press-fitted into the bearing holding hole of the bearing housing, compressive stress in a circumferential direction and a radial direction is generated inside the sliding bearing, and the sliding bearing is fixed to the bearing holding hole.
As a typical configuration of circumferential direction both ends of the sliding bearing, there are a butt type and a clinch type. JP-A-2004-11898 (see FIGS. 1 and 6 and the like) discloses the butt type. Circumferential direction both end surfaces of a sliding bearing are flat surfaces and have a space between the circumferential direction both end surfaces in a free state before being press-fitted into a bearing holding hole. When the sliding bearing is press-fitted into a bearing holding hole of a bearing housing, the circumferential direction both end surfaces come in contact with each other.
JP-A-6-264928 discloses the clinch type. A cylindrical bearing includes a clinch configured with a convex portion and a concave portion on longitudinal direction both ends of a plate material in a developed state before being formed into a cylindrical shape. The plate material is formed into the cylindrical shape, and at the same time, the convex portion and the concave portion mesh with and connect to each other and the cylindrical bearing is manufactured.
Further, in a sliding bearing in which a pair of split bearings butts against each other to form a cylindrical shape, there have been made proposals of decreasing a strength of an circumferential direction end locally by forming a convex portion, a hole, or a slit on the circumferential direction both ends or one of the circumferential direction ends of the split bearing (see JP-U-63-51923, JP-A-5-44729, and JP-A-2005-90650). In these, in a state that the pair of the split bearings is assembled into respective semicylindrical shape bearing holding holes of a split type bearing housing, the split type bearing housing is fastened with a bolt to be integrated. In the fastening process with the bolt, the circumferential direction end of the split bearing is plastically deformed locally, or an elastic deformation amount of the circumferential direction end is increased, so that circumferential direction compressive stress generated inside the sliding bearing is decreased.